You're basically on the hook for the full underlying value of the options less the premium received if you hold till expiration and by expiration the company has gone bankrupt (i.e. $0/share or delisted assuming zero).
Basically you're buying those shares as agreed at that strike price.
It probably won't go to zero right away though. You'd buy a bunch of shares, which are listed on NYSE now, but worse comes to worse if they do go bankrupt or delisted, it may probably trade pink sheet as a penny stock, before going to zero or bought out.